The efficient packaging of products has become a major factor in the profitability of many product lines. Items such as food stuffs, for example, are automatically filled in packages under sanitary conditions. These filled packages are then transported to what are generically know as "case machines". Case machines are those machines which take a plurality of individual packages and place them in cases for shipment in the distribution process. Case machines, however, are notorious for down time. Mechanically packing cardboard boxes into larger cardboard boxes requires precise adjustment of the case machine, particularly since tolerances are tight and paper products, at least, cannot withstand excessive force.
Nevertheless, efficient operation of a manufacturing facility requires that the up stream machinery continue to operate without interruption. It is undesirable to stop and start filling or packaging operations because restarting the case machine is difficult. In addition, continuous operation will produce more product, since the down time for each machine would not be linked to, or added to, down time for other units.
In the past case machines and other down stream machines have been linked close together requiring both to stop when either one does. In an attempt to provide some accumulation the operations have been spaced apart with the connecting conveyor providing brief accumulations. Thus if operation of the down stream machine is interrupted, the up stream machine will merely add additional objects to the conveyor until the down stream machine is repaired. In some instances, serpentine conveyor paths have been used to receive product continuously from the up stream operation. Continuously adding more product to a serpentine conveyor which is not feeding to the down stream unit causes a continuous buildup of pressure on the product. If the coefficient of friction is 0.25, which is a reasonable value for paper products sliding on conveyor belts, 25% or 1/4 of the weight of the total number of products is pushing on those front few packages which have been stopped while the case machine or other down stream unit is being repaired.
One method has been proposed for accommodating a collection of articles being produced up stream while the down stream processing unit is not in operation. These devices, generally called accumulators, are designed to pick up the articles which pass along on a conveyor by lifting the edges of the container which extend over the sides of the conveyor. This method has two distinct disadvantages. First there is often little space on the object for the lifting mechanism to engage, and thus the possibility exists that objects will not be caught by the lifting mechanism. Second while some objects such as packaged frozen pizzas are flat and intended to be shipped in containers which are relatively long and wide compared to the height of the package, many products, such as, for example, breakfast cereals, specialty crackers, and the like have as their longest dimension the height of the package. Consequently, with these products vertical lifting of the package is limited by the ceiling height in the assembly room and little accumulation is available.
Accordingly, it is an object of the present invention to provide a device which is suitable for accumulating discrete objects which are carried between an up stream location and a down stream location while remedying the deficiencies of the prior art. Specifically, it is an object of this invention to eliminate the need for long, serpentine conveyors which use an inordinate amount of floor space. It is also an object of this invention to provide a machine for accumulating those objects in a machine which is suitable for use where floor space and ceiling height would otherwise limit the use of an accumulating type device.